Divya Singhatwaria 77e3a8c5e4 gpu: nvgpu: ga10b: Add request_idle ce ops ...

Issue observed:
- In GA10B, it was observed that after recovery happens
  ELPG does not engage.
- It was because, after CE reset, when nvgpu_submit_twod test
  was run to engage ELPG, IDLE_FLIPPED_PWR_OFF signal was asserted.
- This means that when ELPG was engaged (engine is in PWR_OFF),
  some idle signal flips (becomes non-idle) and this causes
  IDLE_SNAP. After IDLE_SNAP is hit, ELPG will not engage further.
- After debugging from WAVES, it was observed that:
  LCE0/LCE1 are not done with the reset sequence.
- The state of these LCE is RESET0. A pri request (pri read
  to NV_CE_PCE_MAP register in CE) is seen that kicks it out of
  RESET0. After this state, it goes through few states to update
  some internal states (states RESET1/RESET2/PCE_MAP etc) and then
  eventually settles down to IDLE state.

Solution:
- Read ce_pce_map_r register in recovery sequence (after ce reset).
- It is observed that when this read is added recovery is complete
  and post that when nvgpu_submit_two test is executed, ELPG is engaging.
- This means that a pri read is needed after CE reset so that it settles
  to idle state properly and post that ELPG can engage properly.

Bug 200734258

Change-Id: I5bb84921ca62a740fde81ffe6c29ccde4ebb341b
Signed-off-by: Divya Singhatwaria <dsinghatwari@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2554493
Reviewed-by: svcacv <svcacv@nvidia.com>
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Reviewed-by: svc_kernel_abi <svc_kernel_abi@nvidia.com>
Reviewed-by: Mahantesh Kumbar <mkumbar@nvidia.com>
Reviewed-by: Seema Khowala <seemaj@nvidia.com>
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GVS: Gerrit_Virtual_Submit
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

2021-07-15 10:05:02 -07:00

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